The vortex shedding flowmeters commercially available at the present time determine vortex shedding frequencies by measuring the effect of the pressure fluctuations occuring in the immediate vicinity of the bluff body or by detecting the action of sinuating streamlines in a downstream region. In present day technology, the pressure fluctuations accompanying vortex shedding are measured by detecting the side-to-side deflection of the bluff body resulting from the pressure difference across the two sides thereof, or by measuring the deflection of a diaphragm with two sides respectively exposed to two pressure holes open to the two sides of the bluff body, respectively. The side surface area of the bluff body as well as the area of the diaphragm with each side exposed to a single pressure hole is generally limited to a small size. As a consequence, the existing method of detecting the pressure fluctuations accompanying vortex shedding is effective only for the vortices of sizable intensity, which is generally proportional to the square of the fluid velocity. The existing vortex shedding flowmeters employing the aforementioned pressure detection method fail to measure air velocities less than 25 feet per second under the standard condition and the water velocities less than 1.5 feet per second. The cord length of the wing employed in today's vortex shedding flowmeters for measuring the lift force created by the sinuating streamlines produced by the vortices cannot be greater than four times the bluff body width, as the wave length of the sinuation streamlines is about eight times the bluff body width. Consequently, the surface area of the wing employed for detecting the effect of the sinuating streamlines is generally limited to a small size. The existing vortex shedding flowmeters employing a wing fail to measure air velocities less than 20 feet per second and water velocities less than 1.0 feet per second. It is well established fact that the vortices are shed in regular pattern at velocities as low as a few feet per second for air flow under the standard condition and a fraction of a foot per second for water flow. There are numerous applications in the industries where the measurement of air velocities less than 10 feet per second and water velocities less than 1.0 feet per second is required. The present day vortex shedding flowmeters have failed to meet such requirements.